1. Field of the Invention
The present invention relates to contents distribution method and system, particularly relates to contents distribution method and system for enabling encrypting and distributing digital contents and secure accounting.
2. Description of the Related Art
Recently, digital contents such as newspaper articles, a magazine, music, images and software are starting to be distributed utilizing various distribution paths such as the Internet, CD-ROM and satellite communications and in the future, the distribution of digital contents is expected to be further increased. Though many of these digital contents are free, some providers of digital contents desire that in the future, the charge for the distribution of digital contents should be collected.
However, there are generally the following problems for a provider of digital contents to distribute digital contents subject to payment utilizing the above distribution paths and the above problems prevent digital contents subject to payment from being provided.
1) As distributed digital contents are unfairly copied, copyright is not protected.
2) An exact accounting system for digital contents is not established.
3) The amount of the charge for digital contents is small, for example a few tens yen or a few hundreds yen and an accounting system which can correspond to the payment of a small amount is not established.
4) Accounting data may be falsified.
5) Special hardware is required of every terminal utilizing digital contents to be paid and a user utilizing digital contents to be paid is required to considerably invest in facilities.
Therefore, for technique for solving the above problems, “a data broadcast system and a data sink” disclosed in Japanese Published Unexamined Patent Application No. Hei 8-32530 is proposed. In the above “data broadcast system and data sink”, a data broadcast system for encrypting and transmitting data, decoding it on the side on which the data is received and flexibly accounting according to the quantity of decoded data and others is disclosed and technique corresponding to the problems described in above 1) and 2) is disclosed.
For a method of paying a small amount described in above 3), many prepaid systems in which a prepaid card is used are proposed.
However, in the above “data broadcast system and data sink” disclosed in Japanese Published Unexamined Patent Application No. Hei 8-32530, there are problems that a key for decoding is required to be prepared every data type and that there is no measure for falsifying accounting data.
In the meantime, in the above prepaid system which is a method of paying a small amount, a receipt for individual digital contents is not issued, purchase is required to be managed on his/her own responsibility and use in an office and others is unsuitable.